Quantitative Pathology of Nasal Passages in Rats Exposed to Urban Levels of Air Pollution

Lemos, Miriam; Lichtenfels, A.J.F.C.; Amaro, Edson; Macchione, M.; Martins, Mílton A.; King, M.; Böhm, György; Saldiva, Paulo Hilário Nascimento

doi:10.1006/enrs.1994.1046

Cited by 52 publications

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“…Our laboratory performed a series of studies in which animals were chronically exposed to urban levels of air pollution in field experiments (Böhm et al, 1989;Saldiva et al, 1992;Lemos et al, 1994). In these studies, rats living in polluted areas developed inflammatory alterations of the airways and distal lung parenchyma, which impaired lung defense mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Urban Air Pollution Enhances the Formation of Urethane-Induced Lung Tumors in Mice

Reymao

Cury

Lichtenfels

et al. 1997

Environmental Research

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Section: Introductionmentioning

confidence: 99%

Urban Air Pollution Enhances the Formation of Urethane-Induced Lung Tumors in Mice

Reymao

Cury

Lichtenfels

et al. 1997

Environmental Research

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“…Atmospheric pollution in Sao Paulo is high enough to induce adverse health effects on experimental animals. Previous studies using rats as sentinel animals for assessing the chronic effects of air pollution disclosed functional alterations of mucociliary clearance, inflammatory changes along the respiratory tract, and bronchial hyperresponsiveness in exposed animals (13)(14)(15)(16) (17). These experimental findings provide some degree of toxicological support to epidemiological studies that indicate a significant association between air pollution and mortality in Sao Paulo (10,11 59.0/o67.5%, 67.5-76.5%, >76.5%).…”

mentioning

confidence: 99%

Association between air pollution and intrauterine mortality in São Paulo, Brazil.

Pereira

Loomis

Conceição

et al. 1998

Environ Health Perspect

117

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“…Urban air pollution in a heavily industrialized city (São Paulo, Brazil) has been used to produce experimental bronchitis in rats [45,46]. In this case, the lesion develops much more slowly, in 3-6 months, but otherwise shares many of the features expected for a successful model for bronchitis.…”

Section: Small Animal Models Of Chronic Bronchitismentioning

confidence: 99%

Experimental models for studying mucociliary clearance

King¹

1998

Eur Respir J

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Respiratory tract mucus is a viscoelastic gel, the rheological properties of which are determined mainly by its content of mucous glycoproteins and water. The rheology and quantity of mucus, in concert with ciliary factors, are the major determinants of mucociliary clearance.A wide range of animal models for studying the secretion and clearance of mucus are available. Ex vivo models, such as the frog palate or excised bovine trachea, provide direct, meaningful data regarding the clearability of mucus. Rodent models of chronic bronchitis, based on irritant gas or cigarette smoke exposure, show important features of the human condition in a relatively short time. The rheological characterization of mucus is made difficult by the small quantities obtainable, particularly from normal animals.Large animal models, such as the dog or sheep, although more expensive, offer many advantages, such as the ability to carry out long-term serial measurements, and to make integrated measurements of the clearance of mucus, ciliary function, epithelial ion transport, and the rheology of mucus in the same preparation. Eur Respir J 1998; 11: 222-228 The viscoelastic properties of mucusDue to the cross-linking of glycoproteins, the rheological behaviour of mucus is described as viscoelastic, having characteristics of both a liquid and a solid [1,2]. Viscosity is the resistance to flow, and represents the capacity of a material to absorb energy as it moves. Elasticity is the capacity of a material to store the energy used to move or deform it. With ideal fluids, viscosity is independent of the stress applied. With viscoelastic liquids, such as mucus, viscosity decreases with increasing stress or rate of strain (shear rate). Mucus responds to stress with an initial solid-like deformation, followed by a viscoelastic deformation and finally by a period of steady flow, in which the rate of deformation is constant. Only partial recovery of the strain follows removal of the stress, indicating a permanent deformation of its gel structure. Changes in the viscosity and elasticity of mucus are generally interrelated.Mucus exhibits shear-thinning following exposure to high shear forces, exhibiting a decreased viscosity at low shear rates. Some shear-thinning may be permanent, indicating altered molecular structure, whilst some shearthinning, termed "thixotropy", may be reversible.The viscoelasticity of mucus can be effectively described by two relatively independent quantities, G* and tangent (tan) δ, which vary with measurement frequency. The mechanical impedance (G*), is the vector sum of viscosity and elasticity; it can be termed the "rigidity factor". Tan δ is the ratio of viscosity to elasticity; it is also known as the loss tangent and can be considered as a "recoil factor". The relative proportions of elasticity and viscosity are important in describing how a material, such as mucus, behaves when it is subjected to external forces. Rheological assessment of mucus Collection of mucusTracheal mucus can be collected by a modificat...

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Quantitative Pathology of Nasal Passages in Rats Exposed to Urban Levels of Air Pollution

Cited by 52 publications

References 0 publications

Urban Air Pollution Enhances the Formation of Urethane-Induced Lung Tumors in Mice

Urban Air Pollution Enhances the Formation of Urethane-Induced Lung Tumors in Mice

Association between air pollution and intrauterine mortality in São Paulo, Brazil.

Experimental models for studying mucociliary clearance

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